A hallmark of autoimmune disease is an increase in the incidence of self-reactive B lymphocytes with the subsequent production of autoantibodies. It seems clear that regulatory defects are intimately associated with the onset, if not the continuance, of autoimmunity. One of the goals of the first phase of this proposal is to determine whether or not there are alternations in the composition of the immune repertoire in select autoimmune mouse strains which are potentially pathogenic to nervous system (NS) tissues. We will evaluate the serum, CSF and brain homogenates for autoantibodies of potential NS importance. We will also examine the integrity of the blood-brain-barrier in individual mice. Then we will examine the lymphoid and NS B cell repertoire and selection of V gene families in these mice just prior to the onset of autoimmunity and during the time of overt autoimmunity. This will be accomplished by examining the characteristics of B cells to foreign haptens and self antigens with potential NS importance and by examining B cells (both stimulated and unstimulated) for V gene family expression with in situ hybridization and polymerase chain reaction (PCR). The primary goal of second phase of this proposal is to utilize the techniques learned and information gained in order to analyze B lymphocyte specificity and autoantibody production in human SLE patients. We will examine the repertoire and selection of V gene families in the CSF B cells of human SLE patients. This will be accomplished by evaluating paired sera and CSF from individual patients for antibodies directed against important self antigens; examining CSF derived B cells for antibody production against self antigens using antigen and mitogen stimulated culture techniques; examining these cells for V gene family expression using in situ hybridization and V gene sequence using PCR techniques. The NS function of these patients will be evaluated as well. Our approach of asking specific questions about the degree of diversity and specificity of the NS immune response involves a multifaceted evaluation of antigen specificity and immunoglobulin gene family expression. The information resulting from these studies will contribute significantly to our understanding of immune regulation and NS pathology in SLE.